CSCI 3300
Spring 2009
Exercises for Quiz 5

1. We discussed the distinction between two areas of memory: the heap and the run-time stack. Suppose that variable p has type int*. Which of the following is a correct C++ statement or statement sequence that makes p point to newly allocated memory in the heap?

   1. *p = new int;
   2. p = new int;
   3. p = new int*;
   4. int x; p = &x;
   5. int x; *p = x;

   Answer

2. Suppose that p is defined to point to memory as in the preceding question. Which of the following stores 25 in the integer variable to which p points.

   1. p = 25;
   2. p* = 25;
   3. *p = 25;
   4. p = *25;
   5. p *= 25

   Answer

3. Suppose that a C++ program contains the following statements.

     int* p;
     p[0] = 1;
   

   Which of the following is a true statement about what happens?
   1. Performing those statements can cause unpredictable results
   2. The program containing those statements will get a fatal compile error.
   3. Performing those statements will always lead to a run-time error
   4. There is nothing wrong with those statements; they store 1 into the first cell in an array of integers.

   Answer

4. In a C++ program, x[y] abbreviates

   1. (*x) + y
   2. x + *y
   3. *(x + y)
   4. (x + y)*
   5. x + y

   Answer

5. C++ notation p->x abbreviates

   1. p.(*x)
   2. *(p[x])
   3. (*p)[x]
   4. (p*).x
   5. (*p).x

   Answer

6. Suppose that the following structure type definition is given.

       struct Gadget
       {
         int puff;
         int stuff;
   
         Gadget(int p, int s)
         {
           puff  = p;
           stuff = s;
         }
       };
   

   Which of the following will create a Gadget called g, stored in the run-time stack, whose puff variable contains 4 and whose stuff variable contains 8?
   1. Gadget g(puff = 4, stuff = 8);
   2. Gadget g; puff.g = 4; stuff.g = 8;
   3. Gadget g; puff = 4; stuff = 8;
   4. Gadget g(4, 8);
   5. Gadget g = Gadget(puff = 4, stuff = 8);

   Answer

7. If g is the Gadget created in the preceding question, which of the following will print the value of the stuff variable in Gadget g on the standard output?

   1. cout << g[stuff];
   2. cout << g.stuff;
   3. cout << stuff.g;
   4. cout << Gadget g.stuff;
   5. cout << stuff(Gadget);

   Answer

8. Using type Gadget from the previous question, which of the following will create a new Gadget in the heap, with its puff variable holding 39, and its stuff variable holding 4, and make variable w point to the new Gadget?

   1. Gadget* w = new Gadget(39,4);
   2. Gadget* w = new Gadget(4,39);
   3. new Gadget w(39,4);
   4. new Gadget w(4,39);
   5. new Gadget* w(39, 4);

   Answer